1. Field of the Invention
The present invention relates to a method and an apparatus for producing ozone-containing water.
2. Discussion of the Background
Ozone-containing water is used for sterilizing vegetables, corns, meat, water, or the like or decomposing impurities in water. The ozone-containing water has been previously produced by the so-called bubbling method in which an ozone-containing gas generated in an ozone generator is absorbed into an aqueous liquid or by a method in which a liquid is caused to flow in a pipe while an ozone-containing gas is introduced into the pipe, and the liquid is agitated by means of baffles arranged in the pipe.
However, the conventional methods as mentioned above have the following problems to be solved.
In general, ozone has a comparatively low rate of dissolving and a comparatively low solubility in aqueous liquids. Since the dissolving rate decreases as the concentration of ozone dissolved in the aqueous liquid approaches the solubility which is specifically determined by pressure and temperature, it is difficult to obtain a solution having a high concentration of ozone. In addition, since impurities in the form of fine particles having a size in the range of about 0.5 to 1 micron are often included in an ozone-containing gas which is used on an industrial basis, and they are consequently introduced into the resultant solution which is produced using such gas, a solution produced by the conventional methods mentioned above is not suitable as a raw material for producing products having a high purity usable for fine chemistry or the like.
Although it is possible to produce a high purity ozone-containing solution by employing (i) a means for removing fine particles from the starting material for the ozone-containing gas using a filter or (ii) a means for filtering a solution with an ozone-containing gas dissolved therein using a filter, a number of man hours are required for practicing the method as proposed above.
A method of dissolving oxygen from air into water using a porous tube has been disclosed (Japanese Laid-Open Patent No. 215339/1987). An ozone-containing water with no impurities can be obtained by employing this method for producing an ozone-containing water. However, this method suffers from the drawbacks that it is difficult to produce an ozone-containing water having a high content of ozone. A high pressure, in the range of 2 to 3 Kg/cm.sup.2 .multidot.G, of an ozone-containing gas is required, and moreover, an ozone generator in larger dimensions to produce an ozone-containing gas on an industrial scale must be designed.
Further, when an apparatus for carrying out the above method is used for producing ozone-containing water, production is achieved at a low efficiency and it is difficult to produce a large amount of ozone-containing water on an industrial scale.
Thus, there remains a need for a method and an apparatus for producing ozone-containing water which do not suffer from the above-mentioned drawbacks.